Composite acrylic fibers and spun yarns

ABSTRACT

A process for the production of composite acrylonitrile fibers using as a solvent a concentrated aqueous salt solution consisting essentially of zinc chloride, which comprises compositely spinning two acrylonitrile copolymers having compositions A and B, said compositions being respectively shown by the following equations: Composition A:

iJnited States Patent 1191 Saji et a1 1 Mar. 4, 1975 1 COMPOSITE ACRYLIC FIBERS AND SPUN YARNS [75] Inventors: Yasuo Saji; Shigeru Ikegami, both of Sunto, Japan [73] Assignee: Toho Beslon Co., Ltd., Tokyo, Japan [22] Filed: Dec. 29, 1971 [21] Appl. No.: 213,726

Related U.S. Application Data [62] Division of Ser. No. 848,796, Aug. 11, 1969,

abandoned.

52 us. c1. 57/140 BY, 161/175, 260/823 51 1m. (:1. D02g 3/24, D02g 3/02, DOld 5/28 [58] Field 61 Search... 57/140 R, 140 BY; 264/171,

[56] References Cited UNITED STATES PATENTS 3,038,237 6/1962 Taylor 161/172 3,039,524 6/1962 Belck et a1 161/177 3,400,531 9/1968 Ohfuka et a1 57/140 BY 3,473,998 10/1969 Spriesterbach et a1. 161/177 FOREIGN PATENTS OR APPLICATIONS 480,454 12/1969 Switzerland 264/D1G. 26 43-4548 2/1968 Japan 44-26410 11/1969 Japan Primary E.\'aminerJohn Petrakes Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT 1 A process for the production of composite acrylonitrile fibers using as a solvent a concentrated aqueous salt solution consisting essentially of zinc chloride, which comprises compositely spinning two acrylonitrile copolymers having compositions A and B, said compositions being respectively shown by the following equations: Composition A:

2(M,, N 4.5) 9(M N 10.5) 36 Composition B:

0.16( V 24 M,, N,, 8 V 24) (M,, V 24N,, 8F; 25

17 M,,+N,,+ 10L,, 30

both of said compositions satisfying the following relations:

(6) A B wherein M represents the content in percent by weight of the hydrophobic comonomer in said acrylonitrile copolymer, N represents the content in percent by weight of the hydrophilic and non-ionizable comonomer in said acrylonitrile copolymer, L represents the content in percent by weight of the ionizable comonomer in said acrylonitrile copolymer, and a and b desig nate comonomers corresponding to composition A and B respectively.

14 Claims, 1 Drawing Figure I I I I 1 u COMPOSITE ACRYLIC FIBERS AND SPUN YARNS This is a division of application Ser. No. 848,796, filed Aug. 11, 1969, now abandoned.

BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates to a process for producing composite fibers and more particularly to a process for the production of composite fibers having various excellent properties such as dyeing property, stripping resistance, and yarn spinning property by preparing composite fibers having novel compositions selected in accordance with the uses of the fibers using an aqueous salt solvent consisting essentially of zinc chloride and then subjecting the fibers to a selected after-treatment.

2. Description of the Prior Art The improvement for acrylic fibers, wherein by providing a permanent crimp to the fibers, the fibers are endowed with a wool-like appearance and hand, and also, the change ofa wool-like hand is prevented by repeated washing, has already been widely and industrially practiced.

As a process for providing a permanent crimp, there has been proposed a process wherein fibers having assymetric cross sections using one kind of spinning solution are employed in the case of providing permanent crimp to acrylic fibers, but, in general, the formation step ofthe fibers is so improved using the specific spinning nozzle disclosed in Japanese Pat. No. 2996/39 that two kinds of spinning solutions having specific compo sitions are combined bimetal-like or sheathcore-like in the longitudinal direction.

However, in the case of wet spinning an acrylonitrile copolymer using an aqueous inorganic salt solution consisting essentially of zinc chloride as the solvent, fibers prepared by spinning two kinds of spinning solutions having known compositions, by a known process, and subjecting the thusspun fibers to an aftertreatment, have such faults that the permanent crimp provided thereto is insufficient. If improvements are attempted to provide a sufficient permanent crimp to the fibers, the yarn spinning property is reduced to degrade the quality of the spun yarns, the two components tend to be readily separated from each other at the conjugated part, the heating discoloration is increased, and all of the color uneveness appears in the dyed product, all of which result in lowering the practijal usage of the final products.

The purpose of providing a permanent crimp to acrylic fibers is, of course, that the value of the final product is increased as compared with ordinary fibers. Besides having a high crimping property, it is also re quired that the desired final products or articles can be smoothly prepared, and that the properties of the final products are not degraded due to fiber properties other than the crimping property.

Generally, fiber properties, including the crimping property, depend on the compositions of the spinning solution, the kind of spinning method, and the solvent. In particular, the properties are influenced by whether the solvent is an organic type or an inorganic type and, when an inorganic type is employed, by the kind thereof An object ofthis invention is to provide a process for producing composite fibers having a good permanent crimping property, without being accompanied with the aforesaid faults, using an aqueous inorganic salt solution consisting essentially of zinc chloride as the solvent.

Composite acrylic fibers are generally spun into yarns and the yarns are then processed or fabricated 5 into the desired articles. In this case, the present inventors have found that the conditions for producing the composite acrylic fibers must be controlled in accordance with whether the composite fibers are spun into a) yarns consisting of almost 100% composite fibers, b) blended yarns with non-shrinkable fibers, or c) blended yarns with shrinkable fibers. For example, when composite fibers suitable for providing blended yarns with either non-shrinkable or shrinkable fibers are employed to form yarns consisting of only composite fibers, textile goods prepared from these yarns are not always satisfactory and in some cases, the hand of such textile goods is bitterly reduced.

Thus, an object of the present invention is to provide a process for producing composite acrylic fibers which may be used for the purposes mentioned above.

The aqueous inorganic salt solution consisting essentially of zinc chloride which is used in the present invention, as solvent, signifies that the aqueous solution contains 50 66 70 by weight whole salts and at least 40% by weight of the salt solvent is zinc chloride. It is well known that such a solution is a good solvent for acrylonitrile polymers.

SUMMARY OF THE INVENTION It has been discovered that in order to obtain composite acrylic fibers having exce]lent properties using the aforesaid solvent, each monomer component of polymer compositions A and B of the composite fibers must be in the range shown below.

Composition A:

2(M, N 4.5) 9(M N 10.5) 5. 36

19 M,,+N,,+ l0L,, 32.5

Composition B:

0.16(\ 24 M N 8 V24) (M V. 24 N,, 8)- s 25 The following relationships exist between the constituents of composition A and composition B:

( u a) I) b) 1 a a u) I: b) s When used as blended yarns with more than 20 percent by weight of non-shrinkable fibers:

u u u) l: b b) 2 a) When used as blended yarns with more than 20 percent by weight of shrinkable fibers:

(M, N, L (M, N,, L,,) '5 4o (9) wherein M represents the content in percent by weight of hydrophobic comonomer, in the acrylonitrile copolymer, having a solubility of less than 10g./100 ml. in water at 20 C., such as methyl acrylate, methyl methacrylate, and vinyl acetate;

N represents the content in percent by weight of hydrophilic comonomer, in the acrylonitrile copolymer, other than an ionizable group, having a solubility of higher than 50 g./l ml. in water at 20 C., such as acrylamide, and methacrylamide;

L represents the content in percent by weight of an ionizable comonomer, in the acrylonitrile copolymer, such as sodium allylsulfonate and sodium methallylsulfonate; and

a and b designate comonomers corresponding to composition A and composition B, respectively.

BRIEF DESCRIPTION OF THE DRAWING The FlGURE represents a spinning nozzle which may be utilized in the practice of the present invention.

DETAlLED DESCRIPTION OF THE INVENTION By non-shrinkable fibers are meant such fibers that shrink less than an average of percent when a single fiber is treated for 30 minutes in hot water of 95100C., under a non-stretched condition. By shrinkable fibers are meant such fibers that shrink more than an average of 5 percent when a single fiber is subjected to the aforesaid treatment.

Methods for preparing compositions A and B are disclosed in Japanese Pat. No. 1024/63. According to the above teachings, it is necessary that one of the aforesaid compositions A or B, for the copolymer, contain more ionizable groups than the other; and it is desirable that the difference in content of ionizable groups be higher than 50 milliequivalents per 1 kg. of the copolymer.

Composite acrylic fibers prepared by wet spinning using two kinds of acrylonitrile copolymers, the main difference between which is ionizable groups content, using an aqueous inorganic salt solution consisting essentially ofzinc chloride as a solvent have the disadvantage that the textile goods produced from the composite fibers, after dyeing, give color uneveness which bitterly reduces the commercial value of the textile goods.

This phenomenon is varied to some extent according to the kinds of dyes and dyeing conditions employed, but in the case of dyeing the acrylonitrile synthetic fihers with ordinary cationic dyes under conventional conditions, the textile goods tend to suffer the aforesaid fault.

As a result of investigations directed toward solving such a disadvantage, the present inventors have discovered the following.

Each of the spinning solutions A and B, to be used for producing the composite fibers, is spun individually, using a conventional spining nozzle under conditions wh ch are the same as when spinning composite fibers to provide fibers consisting of either component A or B. These fibers are dyed in the same bath under the following conditions:

Dyestuff: Astrazone Blue SGL (Trade Name), manufactured by Bayer in Germany. 1.0% (o.w.f.)

Retarder: Ospin TAN (Trade Name), manufactured by Tokai Seiyu Co., Ltd. 1.0% (o.w.f.)

Bath ratio: 1:80

Dyeing temperature: 98-100 C.

Dyeing period: minutes.

When the content of ionizable groups between both types of fibers as prepared above greatly varies, a difference in color tone results, the difference being measured by means of a grey scale for discoloring and fading of I18 L-O804 (Testing method of color fastness).

When the composite fibers prepared from composi tions A and B are employed, the difference in color tone between which is less than third class, the aforesaid disadvantage is bitterly observed in the textile goods dyed by various cationic dyes.

As a result of investigating the above, using sodium allylsulfonate and sodium methallyl sulfonate as the monomer having the ionizable group, it has been confirmed that when the difference of the content of ionizable groups in both A and B is less than 0.35 percent, the determination by the aforesaid grey scale test becomes higher than fourth class, but when the difference is higher than 0.35 percent, the result becomes less than third class.

Equation (6), shown above, represents the restriction conditions based on these discoveries, which shows that the process of the present invention is fundamentally different from the process disclosed in Japanese Pat. No. 1024/63.

Moreover, there have been proposed various methods for providing the difference in content of comonomers having other than ionizable groups, between compositions A and B, for the composite fibers, but the process of this invention is different from any of these known methods since the present invention provides for the difference of content of the hydrophobic comonomer and the hydrophilic comonomer in the numerical ranges shown above.

A method of providing the difference in content of the hydrophilic comonomer and hydrophobic comonomer is disclosed, e.g., in Belgian Pat. No. 679,314 but the composition ranges disclosed therein are completely different from the ranges of the present invention. When the composite fibers are prepared from the compositions disclosed in the Belgian Patent using a solvent consisting essentially of zinc chloride, good dyeing property is not obtained, the composite fibers are readily separated at the conjugated part, and discoloration by heating is increased; all of which results in reducing the commercial value of the products made therefrom. Thus, by the teachings of the Belgian Patent, the objects of the present invention cannot be obtained and hence the process of this invention is completely different from that of the Belgian Patent in pur- The physical properties such as strength and elongation ofthe composite fibers thus obtained must be normal, and otherproperties of the fibers are determined according to the following standards:

Test A: Composite fibers are treated for 15 minutes Test Composite fibers are dyedby cationic dyes according to a conventional method. The single fiber thus dyed is cut into a length of'about cm. and the opposite ends are fixed to two papers, each about 1 cm. X 1 cm. respectively. One of the papers is fixed and the 5 in hot water of 95-l00C. under no tension and then other is twisted 200 revolutions in one direction and dried in a steam dryer at about 60 C. immediately thereafter is twisted-400 revolutions in It is required for the composite fibers employed in the opposite direction. Thereafter, the free end is again the present invention that the number of crimped fibers twisted 200 revolutions in the former direction. The formed by the treatments be more than 15/25 mm. H) twisting speed is revolutions per second. fiber length. The middle portion (about 1 cm.) of the thus-treated Test B: A load of 0.5 mg./d. is applied to a single fiber fiber is microscopically observed and the area where of about 5 cm. in length and "subjected to the treatcomponents A and B are clearly separated in the mid ments outlined in test A, the system is treated for die Portion is defined to be stripped'fiberminutes in hot water of 80 C., and then the length (l 15 It is required that when 30 fibers are Subjected mthe thereof is measured, stripping test, theproportion of the strippedfibersbe The single fiber is then dried for minutes at 60 c. less than 20 Permt of the fibers testedwhile l i h l d as Shown above and the length The above-mentioned tests are convenient in order (1 ()fthe fib i measured A l f300 is to determine the practical utilities of the composite fither applied t th fib d again h length 1 is 20 bers; specifically, testsA andB are suitable for evaluatmeasured ing the permanent crimp, test C for evaluating the dis- The mean v l f h l h f 10 fib must Sap coloration by heating, and 'test D for evaluating the isfy the following relations: smppmg l'fislstancfi As mentioned above, according tothe present inven- (l3 -1 )/1 X 100 Z 4 tion, a process is provided for producing compositefi- 1 -1 1 X 0 z 2 bars having excellent properties, besides an excellent permanent crimping property, and the composite fibers 5:2 g f'i a? mmutes at of the present invention are required to have normal 235 11 0t e reflect've physical properties such as tensile strength and elonga- 7 e l ers ls measure at wave length of tion and must pass the standards outlined in tests A, B, 4-0 m before and after the above treatment by means C and D Shown above gi z ggz The followmg relatlon must be The results of measuringthe properties of the compositefibers prepared by using the two spinning solu- [R (AftertreatmenU/Rm (B f treatment X 100 tions or components shown in Table 1, from No. l to 2 35 No.14, are shown n Table 2.

' Table 2 One ComponentNo. l 2 3 4 5 6 7 8 9 l0 l1 l2 l3 14 Other ComponentlNo.

X X X 2 x m 3 x 4 5. T.

' Table l Satis- Satis- Content fying fying of ioniequaequa- Content of hydro- Content of hydro zable co tion tion phobic comonomer philic comonomer monomer l and 2 3 and 4 Methylvinylacrylmethacrysodium No. acrylate acetate amide lamide methacrylsulfonate l 9.5 l.5 O 2 6.6 1.3 0 3 4.2 1.3 4 10.5 0.5 1.3 5 9.1 2.2 1.3 0 6 8.0 4.2 L5 0 7 8.0 3.3 1.5 0 8 8 2 0.5 1.5 0 9 6.5 5.6 1.5 [0 6.3 4.0 L3 0 l l 6.0 2 l 1.3 l2 4.8 4.0 l.3 l3 9.) 5.0 l.3 14 7.3 2.5 1.3 0

Table 2 4 Continued One Component No. l 2 3 Other Component No.

wherein: the combination of both components providing fibers having normal tensile strength and elongation and passing tests A, B, C, and D.

.r the combination of both components providing fibers which failed to pass at least one of tests A, B, C, and D.

the combination of both components providing fibers having a bad spinning property, which were judged to have failed to pass the tests before testing or were not subjected to the tests.

' Z the combination of both components satisfyin'g equations (l), (2), (3), (4), and (6) out- I lined above.

The results in Table 2 show that the better composite fibers are obtained when the combination of the two components satisfies equations (1), (2), (3), (4), (5) and (6).

The good composite fibers of 4 deniers obtained by using the combination of the two components corresponding to the marks shown in Table 2 were bias-cut into 75-1 mm. lengths, and yarns were produced from a) 100 percent composite fibers, b) a mixture of composite fibers and c) other fibers, by means ofa worsted spinningmachine. The yarns were treated for minutes by steam at 105 C. to sufficiently exhibit the latent crimp ofthe composite fibers, and then dyed and dried according to conventional methods. The band and other properties of the dyed yarns were determined by three experts, and the results are shown in Table 3.

In the Table, blended yarns with non-shrinkable fibers signify blended yarns consisting of composite fibers and more than 20 percent by weight of fibers having a hot water shrinkage of not more than 5 percent, such as ordinary acrylic staple, wool, rayon staple, and the like. Also, blended yarns with shrinkable fibers signify those fibers consisting of composite fibers and more than 20 percent by weight of fibers having a hot water shrinkage of higher than 5 percent.

Of course, the hand of the dyed yarns depends on the kind of fibers, the deniers, the count of spun yarns, the twisted number, etc. However, in the case of evaluating the yarns of composite fibers dyed in a conventional manner, the crimp of the composite fibers mainly con-- tributes to the hand of the yarns, and hence factors other than whether the blended yarns are made with shrinkable fibers or non-shrinkable fibers are omitted and the results are shown in Table 3 above.

Equations (7), (8), and (9), mentioned above, were o dbassd these di overi In the case of blending the composite fiber with both shrinkable fibers and non-shrinkable fibers, when the proportion of both fibers is higher than 20 percent by weight, the yarns are largely influenced by the component present in the larger proportion, however, when the proportion of both components in higher than 20 percent by weight, and also the proportion of the shrinkable fibers is the same as that of the nonshrinkable fibers, the influence of the shrinkable fibers is larger. Equations (7), (8), and (9) are applied from this Y f'WPQ PI;

When, in general, composite fibers in which two components have been combined bi-metal like are subjected to an outer force such as friction, the fiber tends to be separated or stripped into each component, at the conjugated part.

If such stripping occurs predominantly during the production of the textile goods or during their use, the fault becomes fatal. Such a stripping property depends on the components of both compositions and the spinning method. Thus, the component ranges of the process of this invention, shown above by numerical equations, have been determined with great care but sufficiently good results have not been obtained by defining only the polymer components.

Table 3 Component (Ma+Na+La)- Yarns Con- Union yarns Union yarns (Mb+Nb+Lb) taining with'nonwith shrink- Comp. Comp. b wt. shrinkable able fiber A B comp. iber fiber 7 l [.8 good good good 6 l 2.7 had good good 14 8 0.9 good bad good 10 8 1.6 ood good good 6 2 5.8 ad good bad composite fibers are guided around a metallic rotary roller having a surface temperature of higher than 120 C., while spreading the tow to a width of (total denier 0.34.8) X 10 cm., to contact both surfaces of the tow to the surface of the roller, whereby the fibers are heated and stretched to 1.1-1.4 times, and then the tow are subjected to mechanical crimping to improve the opening property of the tow. Thereafter, the tow are treated for a short period of time, less than 3 minutes. and preferably less than 1 minute, with hot water at a temperature of higher than 80 C., or with steam at a temperature of lower than 130 C., under substantially no tension state of less than 0.01 g./d., whereby the aforesaid stretched portion is substantially relaxed.

It is considered that by stretching the tow while contacting them with a hot roller, the molecules in both components of the composite fibers, in which the two components of the bi-metal like, approach each other to increase the adherent force and also to increase the resistance to stripping. From this principle, if the surface temperature of the roller is lower than 120 C., the mobility of the molecules is less, thereby reducing the aforesaid effect. It is also effective to uniformly contact the tow with the surface of the roller while spreading as mentioned above.

Also, if the stretching ratio of the fibers is less than 1.1 times, the effect is less, while if the stretching ratio is higher than 1.4 times, the fibers are cut or deteriorated locally.

On the other hand, since such secondary stretched fibers have a hot shrinking property to make the handling of the composite fibers difficult or reduce the appearance and hand of the textile goods, it is necessary to conduct the relaxing operation so that the hot water shrinkage of the fibers is less than 5 percent.

In this case, if the tow stretched by the contact with the hot roller are immediately shrunk, the single fibers are slightly fixed together in a unit of several to about 30 fibers to form unopened portions and uneven shrinkage. Therefore, it is desirable to shrink the fibers after improving the opening property by means of passing, e.g., a mechanically crimping machine.

As the opening treatment is made for preventing the occurrence of the aforesaid faults, the treatment is not necessarily conducted by the mechanically crimping machine.

It follows from the properties of composite fibers that when the composite fibers are secondarily stretched and relaxed by the aforesaid means, crimping occurs partially. However, when the composite fibers are once crimped to some extent during the producing step thereof, the formation of crimp in subsequent steps becomes easy; but if the extent of crimp during the pro ducing step of the fibers is excessive, it deleteriously affects the yarn spinning property, and hence it requires such complicated operations that the crimp formed again is removed or reduced and a mechanical crimp for improving the yarn spinning property of the fibers is applied again to the fibers.

1n the process of this invention, the shrinkage step is conducted in a short period of time of less than 3 minutes with hot water or steam of 80l30 C. Accordingly, the hot water shrinkage of the fibers can be reduccd to the desired level, while controlling the extent of crimp to the proper level, thereby not deleteriously influencing the yarn spinning property of the fibers. Thus, the process of this invention is quite effective in that besides the above, the stripping resistance of the composite fibers is improved and the occurrence of crimp is simultaneously improved.

The present invention will be further illustrated by the following non-limiting example.

Example Two kinds of spinning solutions each containing 9 percent by weight of the acrylonitrile copolymer shown below were prepared using an aqueous solution containing 55 percent by weight zinc chloride and 3 percent by weight sodium chloride. and using hydrogen peroxide as the catalyst.

Copolymer A: 87.2 percent by weight acrylonitrile, 8.0 percent by weight methyl acrylate, 3.3 percent by weight acrylamide, and 1.5% by weight sodium methallylsulfonate;

Copolymer B: 89 percent by weight acrylonitrile, 9.5 percent by weight methyl acrylate, and 1.5 percent by weight sodium methallylsulfonate.

The spinning solutions thus prepared were composited through a spinning nozzle having 7,000 holes of 0.12 mm. in diameter for spinning the composite fibers, having the structure shown in FIG. 1 of the accompanying drawing, and then spun into a coagulating bath prepared by twice diluting the above-mentioned solvent with water at 10 C. through nozzle hole 1. The fibers were then washed with water while subjecting the fibers to a stretch of three times, stretched four times in hot water of C., and then relaxed to 8 percent in a drying process at 150 C. In FIG. 1, A and B respectively indicate copolymer A and copolymer B. Prior to the above-noted relaxing step, the fibers were relaxed to 15 percent in hot water of 98 C.

The tow of 4 deniers per filament thus obtained was spread to 4 cm. in width, contacted with four metallic rotary rollers each heated to 150 C. to be subjected to secondary stretching of 1.25 times and, after improving the opening property of the fiber bundle by means of a mechanical crimping machine, was treated for 30 seconds in saturated steam under a tension of 0.01 g./d., whereby the stretched portions subjected to the secondary stretching process were relaxed.

The compositions of components A and B in this example satisfied all equations (1)(9) shown above, and the properties of the composite fibers thus prepared were as follows:

Denier: 4 d

Dry strength: 3.2 g./d.

Dry elongation: 34 percent Knat strength: 2.2 g./d.

Knat elongation: 21 percent Hot Water shrinkage: 2 percent Result of Test A: 28/25 mm.

Result of Test B: (1 l )/l 9; (I z)/ 4 Result of Test C: 95

Result of Test D: 0 percent The fibers were bias-cut into 75-115 mm. lengths and spun into yarns of 2/30 metric count having the following compositions by means of a spinning machine:

I. 100 percent by weight composite fibers;

I1. blended yarns of 50 percent by weight of composite fibers and 50 percent by weight of regular acrylic staple of 5 deniers having a hot shrinkage of 1.3 percent; 1

111. blended yarns of 50 percent by weight of composite fibers, 30 percent by weight of the aforesaid regular acrylic staple, and 30 percent by weight wool;

IV. blended yarns of 40 percent by weight of composite fibers, 30 percent by weight of the aforesaid regular acrylic staple and 30 percent by weight of rayon staple;

V. blended yarns of 40 percent by weight of composite fibers, 20 percent by weight of the aforesaid regular acrylic staple, and 40 percent by weight of acrylic top of deniers having a hot water shrinkage of 21 percent.

When these yarns were treated with steam of 105 C. to develop the latent crimp, and dyed by a conventional method, dyed yarns having good appearance and hand could be obtained in all cases.

For comparison, without applying the secondary stretching, the fibers were subjected to mechanical crimping directly after drying but in such fibers, the result of test D became 30 percent, that is, a larger proportion of fibers were stripped by the friction test.

Also, two kinds of composite fibers were prepared by a procedure the same as the above using the combination of a spinning solution having the following composition and composition A or B of this invention;

Comparative spinning composition: 90.6% by weight acrylonitrile, 6.0% by weight vinyl acetate, 2.1% by weight methacrylamide and 1.3% by weight sodium allylsulfonate.

However, the result of test A was less than /25 mm. test B was failed, and composite fibers having a good permanent crimp were not obtained in any of these cases.

in addition, the above composition did not satisfy equations l and (3) shown above, that is, it was outside the range of this invention.

What is claimed is:

1. Composite acrylonitrile fibers comprising acrylonitrile copolymers A and B, said copolymers A and B comprising acrylonitrile and comonomers copolymerizable therewith; wherein the amount of said comonomers in said acrylonitrile copolymer A is shown by the following relationships:

wherein the amount of said comonomers in said acrylonitrile copolymer B is shown by the following relationships:

0.16 V24 M,,N 8 V24) +(M V24 N,,

8) 25 and 17 M +N +l0L 30;

wherein the compositions of said acrylonitrile copolymers A and B are related to satisfy the following relationships;

( u D N(1) land wherein M represents the amount, in weight percent, of hydrophobic comonomer in said copolymers A and B, said hydrophobic comonomer having a solubility in water at C of less than 10 g./l00 ml.; wherein N represents the amount, in weight percent, of hydrophilic comonomer, which does not contain an ionizable group, in said copolymers A and B, said hydrophilic comonomer having a solubility in water at 20 C of at least 50 g./l00 ml.; wherein L represents the amount, in weight percent, in said copolymers A and B of an ionizable comonomer selected from the group consisting of sodium allylsulfonate and sodium methallylsulfonate; and wherein a and b designate comonomers corresponding to copolymers A and B, respectively.

2. The composite fibers of claim 1 wherein said hydrophobic comonomer is methyl acrylate, methyl methacrylate or vinyl acetate.

3. The composite fibers of claim 1 wherein said hydrophilic comonomer is acrylamide or methacrylamide.

4. Spun yarns comprising at least percent by weight of the composite acrylonitrile fibers of claim 1, the composition of said composite acrylonitrile fibers satisfying the following relationship:

(M N L (M N L 2.5.

5. The spun yarns of claim 4 wherein said hydrophobic comonomer is methyl acrylate, methyl methacrylate, or vinyl acetate.

6. The spun yarns ofclaim 4 wherein said hydrophilic comonomer is acrylamide or methacrylamide.

7. Spun yarns comprising a blend of the composite acrylonitrile fibers of claim 1 and at least 20 percent by weight of nonshrinkable fibers, the composition of said composite acrylonitrile fibers satisfying the following relationship:

8. The spun yarns of claim 7 wherein said nonshrinkable fibers comprise fibers that shrink less than an average of 5 percent when a single fiber is treated for 30 minutes in water of a temperature of from to C, under non-stretching conditions.

9. The spun yarns of claim 7 wherein said hydrophobic comonomer is methyl acrylate, methyl methacrylate or vinyl acetate.

10. The spun yarns of claim 7 wherein said hydrophilic comonomer is acrylamide or methacrylamide.

11. Spun yarns comprising a blend of the composite acrylonitrile fibers of claim 1 with more than 20 percent by weight of shrinkable fibers, the composition of said composite acrylonitrile fibers satisfying the following relationship:

12. The spun yarns of claim 11 wherein said shrinkable fibers comprise fibers that shrink more than an average of 5 percent when a single fiber is treated for 30 minutes in water of a temperature of from 95 to 100 C, under non-stretching conditions.

13. The spun yarns of claim 11 wherein said hydrophobic comonomer is methyl acrylate, methyl methacrylate or vinyl acetate.

14. The spun yarns of claim 11 wherein said hydrophilic comonomer is acrylamide or methacrylamide. 

1. COMPOSITE ACRYLONITRILE FIBERS COMPRISING ACRYLONITRILE COPOLYMERS A AND B, SAID COPOLYMERS A AND B COMPRISING ACRYLONITRILE AND COMONOMERS COPOLYMERIZABLE THEREWITH; WHEREIN THE AMOUNT OF SAID COMONOMERS IN SAID ACRYLONITRILE COPOLYMERS A IS SHOWN BY THE FOLLOWING RELATIONSHIPS; 2(MN-NA-4.5)2 + 9(MA + NA - 10.5)2 $ 36 AND 19 $ MA + NA + 10LA $ 32.5; WHEREIN THE AMOUNT OF SAID COMONOMERS IN SAID ACRYLONITRILE COPOLYMER B IS SHOWN BY THE FOLLOWING RELATIONSHIPS: 0.16 ($24 MB - NB -8$24)2 + (MB + $24 NB - 8)2 $ 25 AND 17 $ MB + NB + 10L-B $ 30; WHEREIN THE COMPOSITIONS OF SAID ACRYLONITRILE COPOLYMERS A AND B ARE RELATED TO SATISFY THE FOLLOWING RELATIONSHIPS; (MA + N9) - (MB + NB) > AND -0.35 $ LA -LB $ 0.35; WHEREIN M REPRESENTS THE AMOUNT, IN WEIGHT PERCENT OF HYDROPHOBIC COMONOMER IN SAID COPOLYMERS A AND B, SAID HYDROPHOBIC COMONOMER HAVING A SOLUBILITY IN WATER AT 20*C OF LESS THAN 10 G./100 ML., WHEREIN N REPRESENTS THE AMOUNT, IN WEIGHT PERCENT, OF HYDROPHILIC COMONOMER, WHICH DOES NOT CONTAIN AN IONIZABLE GROUP, IN SAID COPOLYMERS A AND B, SAID HYDROPHILIC COMONOMER HAVING A SOLUBILITY IN WATER AT 20*C OF AT LEAST 50 G./100 ML.; WHEREIN L REPRESENTS THE AMOUNT, IN WEIGHT PERCENT, IN SAID COPOLYMERS A AND B OF AN IONIZABLE COMONOMER SELECTED FROM THE GROUP CONSISTING OF SODIUM ALLYSULFONATE, AND SODIUM METHALLYSULFONATE; AND WHEREIN A AND B DESIGNATE COMONOMERS CORRESPONDING TO COPOLYMERS A AND B, RESPECTIVELY.
 2. The composite fibers of claim 1 wherein said hydrophobic comonomer is methyl acrylate, methyl methacrylate or vinyl acetate.
 3. The composite fibers of claim 1 wherein said hydrophilic comonomer is acrylamide or methacrylamide.
 4. Spun yarns comprising at least 80 percent by weight of the composite acrylonitrile fibers of claim 1, the composition of said composite acrylonitrile fibers satisfying the following relationship: (Ma + Na + La) - (Mb + Nb + Lb) < or = 2.5.
 5. The spun yarns of claim 4 wherein said hydrophobic comonomer is methyl acrylate, methyl methacrylate, or vinyl acetate.
 6. The spun yarns of claim 4 wherein said hydrophilic comonomer is acrylamide or methacrylamide.
 7. Spun yarns comprising a blend of the composite acrylonitrile fibers of claim 1 and at least 20 percent by weight of nonshrinkable fibers, the composition of said composite acrylonitrile fibers satisfying the following relationship: (Ma + Na + La) - (Mb + Nb + Lb) > or = 1.0.
 8. The spun yarns of claim 7 wherein said non-shrinkable fibers comprise fibers that shrink less than an average of 5 percent when a single fiber is treated for 30 minutes in water of a temperature of from 95* to 100* C, under non-stretching conditions.
 9. The spun yarns of claim 7 wherein said hydrophobic comonomer is methyl acrylate, methyl methacrylate or vinyl acetate.
 10. The spun yarns of claim 7 wherein said hydrophilic comonomer is acrylamide or methacrylamide.
 11. Spun yarns comprising a blend of the composite acrylonitrile fibers of claim 1 with more than 20 percent by weight of shrinkable fibers, the composition of said composite acrylonitrile fibers satisfying the following relationship: (Ma + Na + La) - (Mb + Nb + Lb) < or = 4.0.
 12. The spun yarns of claim 11 wherein said shrinkable fibers comprise fibers that shrink more than an average of 5 percent when a single fiber is treated for 30 minutes in water of a temperature of from 95* to 100* C, undEr non-stretching conditions.
 13. The spun yarns of claim 11 wherein said hydrophobic comonomer is methyl acrylate, methyl methacrylate or vinyl acetate.
 14. The spun yarns of claim 11 wherein said hydrophilic comonomer is acrylamide or methacrylamide. 